Bob,
The number on the inside is most likely the serial number of the pistol that was in this holster. The letters carved in the holster are usually the GI initials who liberated the holster.
This holster has a lot of wear, and looks rather rough.
Albin Scholle made luger holsters in 1939 that have WaA 170 as yours does. A seldom seen maker for luger holsters, although they did make other holsters, such as the P38, with their maker code "fsx" on them.
Hope this helps,
Matt
